Developing rollers, known, for example, from U.S. Pat. No. 6,714,754 B2, are used in an image forming apparatus for developing an electrostatic latent image on a surface of an image bearing member by use of a non magnetic toner to form a toner image. To obtain good images, the requirements of the developing roller are relatively high, especially with respect to the conductivity, hardness, uniformess of the surface etcetera. Furthermore, it is important that the charge providing layer has a good connection to the base layer to prevent local separation or peeling off of the charge providing layer due to the friction between the charge providing layer and the parts of the non magnetic toner.
By the developing roller according to the above mentioned patent, an elastic intermediate layer is provided between the charge providing layer and the base layer.
However, this has the disadvantage that an additional layer needs to be formed on the developing roller. Such an elastic intermediate layer often comprises a solvent to have a good adherence. Such solvent is not good for the environment. Furthermore, the electrical conductivity of such an elastic layer is relatively poor.